The well-known methods allowing to improve the injection distribution cylinder by cylinder are based on a correction of the engine torque via analysis of the instantaneous crankshaft rotating speed taken in each cylinder. Document Toyota SAE 930 873 describes such a method.
The problem is even more acute when small fuel quantities are to be controlled, such as for example small fuel injections taking place before the main injection in direct-injection diesel engines. These pre-injections are referred to as "pilot injections" by specialists and will be thus called in the text hereafter.
These small injections allow to improve the combustion noise of the pollutant emissions.
Document FR-2,704,023 describes a way of controlling this injection type from quasi-zero pilot injections until detectable pre-injection values are obtained.